Exploring the Mechanism of 4‑Hydroxy-1,3,5-triazine-6-thiol\nCollector on Depressant-Free Flotation Separation of Galena from Sphalerite

The\nflotation separation of galena from sphalerite was commonly\nimplemented under pH > 10.5, which led to the consumption of lime.\nIn this paper, 2-diethylamine-4-hydroxy-1,3,5-triazine-6-thiol (DEHTT)\nwas synthesized and introduced as a highly selective collector to\nperform the depressant-free flotation separation of Pb/Zn sulfide\nminerals. The microflotation results indicated that 8.0 × 10<sup>–7</sup> mol/L DEHTT recovered 94.17% galena and 26.67% sphalerite\nfrom their mixture at pH 8.5 regulated by Na<sub>2</sub>CO<sub>3</sub>, and under the same conditions, sodium isobutyl xanthate (SIBX)\nfloated out 94.94% galena and 50.41% sphalerite, deducing a superior\nflotation selectivity of DEHTT in comparison to SIBX. <i>In situ</i> AFM images displayed the more preferable adsorption of DEHTT on\ngalena in comparison to that on sphalerite. The results of adsorption\nthermodynamics and kinetics inferred that the adsorption of DEHTT\nonto the galena surface was a spontaneous endothermic chemical process.\nXPS further indicated that DEHTT combined with interface Pb atoms\nto form the −S–Pb and −O–Pb bonds. The\nspecial affinity of DEHTT to galena achieved the selective flotation\nseparation of galena from sphalerite without the addition of lime\nand depressants.